Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Hydrothermal Synthesis of Zeolite T From Bentonite Clay: Catalytic Applications and Molecular Docking Analysis(National Information & Documentation Centre-NIDOC, 2025) Taib, H.; Lefrada, L.; Belfennache, D.; Belghit, M. Y.; Benbouzid, M.; Yilmaz, S.; A.Ali, MohamedZeolites are essential materials in modern industries due to their uses as cation exchangers, selective adsorbents, and catalysts. In this study,we report novel procedures for producing zeolite T, which is distinguished by its round crystals that closely resemble Saharan flowers. An investigation was conducted on the hydrothermal synthesis of T zeolite in alkaline aqueous solutions without templates. Zeolite T crystals were synthesized via hydrothermal methods with clay-based aluminosilicate gel containing 1Al2O3, 25SiO2, 6.5Na2O, 2.25K2O, and 350 H2O. Zeolite crystals were formed at a temperature of 130 degrees C, with crystallization durations of 3 and 5 days, respectively, using processed natural bentonite clay as the starting material. A range of analytical methods, such as XRD, FTIR, Raman, SEM, ATD-EDX, BET, ATG, and NH3-TPD, were used to observe the crystallization stages of zeolite T grains.During the synthesis of Zeolite T, samples were collected at various intervals, with the samples taken after three and five days of reaction being particularly noteworthy. The T1 zeolite is identified as a mixture of T2 zeolite and other impurities present in the reaction medium, indicating that T1 zeolite serves as a precursor phase to T2 zeolite (T1 is a germination phase). The analysis revealed that a treatment temperature of 130 degrees C for 5 days is optimal. The nucleation of zeolite T from treated bentonite commenced after 3 days. The results indicate that zeolite T2, composed of uniform crystalline grains formed over 5 days, yields a mesoporous structure with a size of 1.35 mu m and a molar ratio of 1.78 between molar quantities of silica and aluminum of this zeolite (T Zeolite). An analysis of the BET (surface area) revealed a value of 95.75 m2g-1, accompanied by a pore volume of 0.010 cm3g-1. Moreover, the examination of TPD-NH3 desorption revealed a restricted occurrence of the acidic site of Br & oslash;nsted, while a significant number of acidic sites of Lewis were detected. The obtained crystalline zeolite T was examined for its ability to catalyze the Hantzsch reaction. In addition, T2 zeolite prepared was used as a catalyst in the synthesis of the 1,1'-(4-(5-bromo-2-thiophenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-diyl)bis(ethan-1-one) (BTDDB) due to the acidity sites (Lewis and Br & oslash;nsted acid) in the structure of the zeolite. The result of the reaction has shown a good percentage in the synthetic of BTDDB The results of FTIR, UV, 13C NMR, and 1H NMR spectrum analyses revealed that the structure of the 1,4-dihydropyridine compound was well-defined, and the use of molecular docking and density functional theory (DFT) analysis revealed better performance in the inhibition of the macromolecular targets aminodeoxyfutalosine nucleosidase and DNA gyrase subunit B.Article Design of Sulfur Resistant Cobalt Catalysts by Boron Promotion: Atomic Scale Insights(Sakarya University, 2024) Kızılkaya, A.C.The effect of boron promotion on atomic sulfur formation by hydrogen sulfide dissociation on Co(111), flat surfaces of cobalt nanoparticles, was investigated using Density Functional Theory calculations. The results show that on clean Co(111), hydrogen sulfide dissociation proceeds fast due to low activation barriers, yielding atomic sulfur on the cobalt surfaces. Boron promotion hinders the dissociation of hydrogen sulfide due to increased activation barriers. Furthermore, boron prevents the interaction of sulfur compounds with cobalt surface atoms, as these poisons bind on boron. The findings indicate that boron is an effective promoter that can be used to design sulfur resistant cobalt catalysts. © 2024, Sakarya University. All rights reserved.Article Design of Sulfur Resistant Cobalt Catalysts by Boron Promotion: Atomic Scale Insights(Sakarya University, 2024) Kizilkaya, A.C.The effect of boron promotion on atomic sulfur formation by hydrogen sulfide dissociation on Co(111), flat surfaces of cobalt nanoparticles, was investigated using Density Functional Theory calculations. The results show that on clean Co(111), hydrogen sulfide dissociation proceeds fast due to low activation barriers, yielding atomic sulfur on the cobalt surfaces. Boron promotion hinders the dissociation of hydrogen sulfide due to increased activation barriers. Furthermore, boron prevents the interaction of sulfur compounds with cobalt surface atoms, as these poisons bind on boron. The findings indicate that boron is an effective promoter that can be used to design sulfur resistant cobalt catalysts. © 2024, Sakarya University. All rights reserved.Article Citation - WoS: 13Citation - Scopus: 13Application of Work Function Measurements in the Study of Surface Catalyzed Reactions on Rh(1 0 0)(Taylor & Francis, 2018) Çağlar, Başar; Kızılkaya, Ali Can; Niemantsverdriet, J. W. (Hans); Weststrated, C. J. (Kees-Jan)The present article aims to show how work function measurements (WF) can be applied in the study of elementary surface reaction steps on metallic single crystal surfaces. The work function itself can in many cases not be interpreted directly, as it lacks direct information on structural and chemical nature of the surface and adsorbates, but it can be a powerful tool when used together with other surface science techniques which provide information on the chemical nature of the adsorbed species. We here, illustrate the usefulness of work function measurements using Rh(100) as our model catalyst. The examples presented include work function measurements during adsorption, surface reaction, and desorption of a variety of molecules relevant for heterogeneous catalysis. Surface coverage of adsorbates, isosteric heat of adsorption, and kinetic parameters for desorption, desorption/decomposition temperatures of surface species, different reaction regimes were determined by WF with the aid of other surface science techniques.Article Citation - WoS: 6Citation - Scopus: 6Esterification of 1-Octanol on Clinoptilolite-Supported Tio2 Catalysts(Springer Verlag, 2019) Özyağcı, Bensu; Şahin, Volkan; Karabakan, AbdulkerimIn this study, a natural type of zeolite, Clinoptilolite (CLI), is used as a support for TiO2. First, TiO2-supported heterogeneous catalysts originated from the high temperature calcination of TiCl4 groups, which were thermally immobilized on clinoptilolite, were obtained. Powder-XRD and EDX analyzes showed that the oxide form of Ti-immobilized on dealuminated clinoptilolite were formed in the anatase phase, and the zeolite structure was preserved. As seen in TGA/DTA analyzes, this catalyst could be efficient and have high stability for many reactions. Second, the esterification reaction of 1-octanol with acetic acid is used as a reference reaction for this catalyst.Article Citation - WoS: 24Citation - Scopus: 30Solution Electrospinning of Polypropylene-Based Fibers and Their Application in Catalysis(Korean Fiber Society, 2016) Berber, Emine; Horzum, Nesrin; Hazer, Bakí; Demir, Mustafa MuammerSince the dissolution of polyolefins is a chronic problem, melt processing has been tacitly accepted as an obligation. In this work, polypropylene (PP) was modified on molecular level incorporating poly(ethylene glycol) (PEG) as graft segment (PP-g-PEG) in a range of 6 to 9 mol%. Gold nanoparticles were nucleated in the presence of the copolymer chains via redox reaction. The dissolution of the amphiphilic comb-type graft copolymers containing gold nanoparticles (80 nm in diameter) was achieved in toluene and successfully electrospun from its solution. The diameter of composite fibers was in the range from 0.3 to 2.5 μm. The design of the structurally organized copolymer fiber mats provided a support medium for the nanoparticles enhancing the active surface area for the catalytic applications. The resulting composite fibers exhibited rapid catalytic reduction of methylene blue (MB) dye in the presence of sodium borohydride (NaBH4) compared to corresponding composite cast film.Article Citation - WoS: 21Citation - Scopus: 21Palladium-Catalyzed Alkoxycarbonylation of Conjugated Enyne Oxiranes: a Diastereoselective Method for the Synthesis of 7-Hydroxy(American Chemical Society, 2015) Kuş, Melih; Artok, Levent; Aygün, MuhittinPalladium-catalyzed alkoxycarbonylative 1,5-substitution of conjugated enyne oxiranes provides a diastereoselective route to (E)-configured 7-hydroxy-2,3,5-trienoates. The reactions proceeded in a highly stereoselective manner, possibly through sequential formation of π-allylpalladium and σ-vinylallenyl palladium complexes. The major diastereomeric form of the product is determined by the configuration of the alkenyl moiety of the substrate.Article Citation - WoS: 38Citation - Scopus: 36Structural Studies of Geosmin Synthase, a Bifunctional Sesquiterpene Synthase With ?? Domain Architecture That Catalyzes a Unique Cyclization-Fragmentation Reaction Sequence(American Chemical Society, 2015) Harris, Golda G.; Lombardi, Patrick M.; Pemberton, Travis A.; Matsui, Tsutomu; Weiss, Thomas M.; Cole, Kathryn E.; Köksal, Mustafa; Murphy, Frank V.; Vedula, L. Sangeetha; Chou, Wayne K. W.; Cane, David E.; Christianson, David W.Geosmin synthase from Streptomyces coelicolor (ScGS) catalyzes an unusual, metal-dependent terpenoid cyclization and fragmentation reaction sequence. Two distinct active sites are required for catalysis: the N-terminal domain catalyzes the ionization and cyclization of farnesyl diphosphate to form germacradienol and inorganic pyrophosphate (PPi), and the C-terminal domain catalyzes the protonation, cyclization, and fragmentation of germacradienol to form geosmin and acetone through a retro-Prins reaction. A unique αα domain architecture is predicted for ScGS based on amino acid sequence: each domain contains the metal-binding motifs typical of a class I terpenoid cyclase, and each domain requires Mg2+ for catalysis. Here, we report the X-ray crystal structure of the unliganded N-terminal domain of ScGS and the structure of its complex with three Mg2+ ions and alendronate. These structures highlight conformational changes required for active site closure and catalysis. Although neither full-length ScGS nor constructs of the C-terminal domain could be crystallized, homology models of the C-terminal domain were constructed on the basis of 36% sequence identity with the N-terminal domain. Small-angle X-ray scattering experiments yield low-resolution molecular envelopes into which the N-terminal domain crystal structure and the C-terminal domain homology model were fit, suggesting possible αα domain architectures as frameworks for bifunctional catalysis. © 2015 American Chemical Society.Article Citation - WoS: 56Citation - Scopus: 57Dynamic Nuclear Polarization of Spherical Nanoparticles(Royal Society of Chemistry, 2013) Akbey, Ümit; Altın, Burcu; Linden, Arne; Özçelik, Serdar; Gradzielski, Michael; Oschkinat, HartmutSpherical silica nanoparticles of various particle sizes (∼10 to 100 nm), produced by a modified Stoeber method employing amino acids as catalysts, are investigated using Dynamic Nuclear Polarization (DNP) enhanced Nuclear Magnetic Resonance (NMR) spectroscopy. This study includes ultra-sensitive detection of surface-bound amino acids and their supramolecular organization in trace amounts, exploiting the increase in NMR sensitivity of up to three orders of magnitude via DNP. Moreover, the nature of the silicon nuclei on the surface and the bulk silicon nuclei in the core (sub-surface) is characterized at atomic resolution. Thereby, we obtain unique insights into the surface chemistry of these nanoparticles, which might result in improving their rational design as required for promising applications, e.g. as catalysts or imaging contrast agents. The non-covalent binding of amino acids to surfaces was determined which shows that the amino acids not just function as catalysts but become incorporated into the nanoparticles during the formation process. As a result only three distinct Q-types of silica signals were observed from surface and core regions. We observed dramatic changes of DNP enhancements as a function of particle size, and very small particles (which suit in vivo applications better) were hyperpolarized with the best efficiency. Nearly one order of magnitude larger DNP enhancement was observed for nanoparticles with 13 nm size compared to particles with 100 nm size. We determined an approximate DNP penetration-depth (∼4.2 or ∼5.7 nm) for the polarization transfer from electrons to the nuclei of the spherical nanoparticles. Faster DNP polarization buildup was observed for larger nanoparticles. Efficient hyperpolarization of such nanoparticles, as achieved in this work, can be utilized in applications such as magnetic resonance imaging (MRI).Article Citation - WoS: 273Citation - Scopus: 327Transesterification of Nannochloropsis Oculata Microalga's Lipid To Biodiesel on Al2o3 Supported Cao and Mgo Catalysts(Elsevier Ltd., 2009) Umdu, Emin Selahattin; Tuncer, Mert; Şeker, ErolIn this study, we present the activities of Al2O3 supported CaO and MgO catalysts in the transesterification of lipid of yellow green microalgae, Nannochloropsis oculata, as a function of methanol amount and the CaO and MgO loadings at 50 °C. We found that pure CaO and MgO were not active and CaO/Al2O3 catalyst among all the mixed oxide catalysts showed the highest activity. Not only the basic site density but also the basic strength is important to achieve the high biodiesel yield. Biodiesel yield over 80 wt.% CaO/Al2O3 catalyst increased to 97.5% from 23% when methanol/lipid molar ratio was 30.